The efficacy of hepatitis B immune globulin (HBIG) with two hepatitis B virus (HBV) vaccines was investigated for prevention of vertical transmission of HBV to infants born to e antigen-positive HBV carrier mothers. Infants received 150 mg of the F(ab')2 fraction of HBIG intravenously within 2 hr of delivery, and serum titers of antibody to hepatitis B surface antigen (anti-HBs) were kept greater than 1:4 (passive hemagglutination) by subcutaneous injection of HBIG thereafter. HBV vaccine was started three or six months after delivery. Of 50 infants older than nine months, 49 were actively immunized against hepatitis B surface antigen. Vaccine containing alum adjuvant immunized the infants in a shorter period than did vaccine without adjuvant. Serum titers of anti-HBs of actively immunized infants were well maintained afterward. None of the infants treated with HBIG and HBV vaccine was positive for serum antibody to hepatitis B core antigen at 12 months of age. No side effects were observed.

A protein having Mr of more than 900K (900,000) was isolated by chromatography on a column of Sepharose 4B coupled with solubilized elastin, followed by sucrose density gradient centrifugation. The protein is composed of several disulfide-linked subunits. SDS-polyacrylamide gel electrophoresis and immunoblotting indicated that two of the subunits are identical with the heavy chains of IgM and IgG, and one is immunologically related to the heavy chain of IgA. The results suggested that this protein is a new protein that belongs to the category of, or is closely related to, the immunoglobulins. As described in the succeeding paper, it has cell-binding activity (Fukamizu et al. (1986) J. Biochem. 100, 843-848). We tentatively refer to this protein as "cell-binding immunoglobulin-like protein (CIP)."